Basic Concepts in Basic Concepts in Dysmorphology

Basic Concepts in
Dysmorphology
Samia Temtamy* & Mona Aglan**
*Professor of Human Genetics
**Professor of Clinical Genetics
Human Genetics & Genome Research Division
National Research Centre, Cairo, Egypt
O tli
Outline
y Definition of dysmorphology
y Definition of terms routinely used in the description of
birth defects
y Impact of malformations
y The difference between major & minor anomalies
y Approach to a dysmorphic individual:
y Suspicion & analysis
y Systematic physical examination
y Confirmation
C fi
ti off di
diagnosis
i
y Intervention
y Summary
2
D fi iti off dysmorphology
Definition
d
h l
y The term “dysmorphology” was first coined by Dr.
David
D
id S
Smith,
ith USA iin 1960s.
1960
y It implies study of human congenital defects and
abnormalities of body structure that originate before
birth.
y The term “dysmorphic” is used to describe individuals
whose physical features
f
are not usually found
f
in other
individuals with the same age or ethnic background.
y “Dys”
Dys (Greek)
(Greek)=disordered
disordered or abnormal and
“Morph”=shape
3
Definition of terms routinely used in
th description
the
d
i ti off birth
bi th defects
d f t
y
A malformation / anomaly: is a primary defect where
there is
th
i a basic
b i alteration
lt ti off structure,
t t
usually
ll
occurring before 10 weeks of gestation.
y Examples: cleft palate, anencephaly, agenesis of limb
or part of a limb.
4
Cleft lip & palate
Absence of digits (ectrodactyly)
y
Malformation Sequence: A pattern of multiple
defects resulting from a single primary malformation.
y For example: talipes and hydrocephalus can result
from a lumbar neural tube defect.
Lumbar myelomeningeocele
5
y
Malformation Syndrome: A pattern of features
features,
often with an underlying cause, that arises from
several different errors in morphogenesis.
y “Syndrome” from the Greek “running together”.
y Causes of syndromes:
y Single gene disorders (e.g. Apert syndrome)
y Chromosomal disorders (e.g. Down syndrome)
y Microdeletion syndromes (e.g. Prader-Willi syndrome)
y Polygenic disorders (e.g. club foot)
y Environmental causes (Teratogenesis)
(
) ((e.g. Rubella,
congenital viral infection, infant of diabetic mother)
6
Hands & feet of a patient with Apert syndrome
Down syndrome
7
Prader-Willi syndrome
Infant of diabetic mother
with caudal regression
Club foot
y
Association: An association is a group of anomalies
that occur more frequently than would be expected by
chance alone but that do not have a predictable
pattern or unified etiology (e.g. VATER association).
Vertebral anomalies, absence of radius & anal atresia as a part of VATER
association
VATER (VACTERL)= V: vertebral, A: anal anomalies, C: cardiac, TE: tracheoesophageal fistula, R: radial, renal anomalies, L: limb anomalies
8
y
Deformation: Distortion by a physical force of an
otherwise normal structure. This could be due to uterine
malformation, twins or oligohydramnios (e.g. contractures
of limbs and talipes deformity.
deformity
Multiple joint contractures (arthrogryposis)
9
Talipes deformity
y
Disruption: Destruction of a tissue that was
previously normal. Examples of disruptive agents
include amniotic bands, local tissue ischemia or
hemorrhage.
Congenital ring constrictions with amniotic bands
10
y
Dysplasia: Abnormal cellular organization within tissue
resulting in structural changes. For example within
cartilage or bone in skeletal dysplasias (e.g.
achondroplasia).
(1)
Trident hands
T id t h
Trident
hand
d
(2)
11
Radiological findings in achondroplasia: Loss of caudal
widening (1), short long bones of lower limbs (2)
Characteristic features
off achondroplasia
h d l i
Impact of malformations
y About 3% of all children born will have a significant
congenital malformation.
malformation
y These congenital malformations are responsible for a
large
g p
proportion
p
of neonatal and infant deaths.
y They also account for about 30% of all admissions to
pediatric hospitals.
y It is important to recognize both major and minor
malformations as they may lead to the early detection
and intervention of a g
genetic disorder.
12
The difference between major and
minor anomalies
y
Major anomalies are severe, impair normal body
function and require surgery for management (e.g.
cleft palate
palate, congenital heart disease
disease……).
)
y They may be isolated or multiple affecting different
body systems.
y Minor anomalies are primarily of cosmetic
significance (e.g. small ear, fifth finger
clinodactyly
clinodactyly…..).
) They occur with variable frequencies
in the normal population.
13
Significance of minor anomalies
Occurrence of single minor anomaly
15% of all newborns
3% have an associated major
anomaly
Occurrence of two minor anomalies
Less common
11% have an associated major
j
anomaly
14
Presence of 3 or more minor
anomalies
Unusual 1%
90% have an associated major
anomaly
42% of idiopathic MR have 3 or more
80% of which are minor
anomalies
anomalies
External minor anomalies in the head
and neck region and the hand
Constitutes 71% of minor
anomalies
Approach
pp
to a dysmorphic
y
p
individual
I- Suspicion & Analysis
A genetic etiology should be suspected if the child has:
y Congenital anomalies (e.g major anomaly or > 2 minor
anomalies)
y Growth deficit (e.g. short stature or failure to thrive)
y Developmental delay, mental deficit or developmental
regression
y Failure to develop secondary sexual characteristics
y Ambiguous genitalia
y Funny looking kid (FLK)
15
1. History:
y
Pedigree:
Consanguinity increases the risk for an autosomal
recessive (AR) disorder
Family pedigree suggestive of an AR disorder
16
Male patient with similarly affected male siblings or
maternal male relatives suggests X-linked disorder.
Family pedigree suggestive of an X-linked disorder
17
Vertical transmission suggests an autosomal dominant
(AD) disorder, specially male to male transmission.
Family pedigree suggestive of an AD disorder
18
History of miscarriages, stillbirths or early neonatal deaths
suggests the possibility of a parental balanced
chromosome rearrangement
rearrangement.
Family pedigree with multiple stillbirths and abortions
19
Pregnancy & family history:
y
y
y
y
y
20
History of uterine malformations or oligohydramnios
may suggestt a possible
ibl aberrant
b
t fforce causing
i
malformation.
Abnormal fetal position or weak fetal movements
suggest abnormal fetal tone.
Placental morphology may give clue to the diagnosis
(e.g.
(e
g large
a ge placenta
p ace a in Beckwith-Wiedemann
ec
ede a
syndrome).
Birth measurements, as symmetrical intrauterine
growth retardation (IUGR) suggests early onset
whereas, asymmetrical IUGR suggests late onset.
Environmental hazards for the fetus:
y
y
y
y
y
21
IInfectious
f ti
agents
t (e.g.
(
viruses,
i
bacteria,
b t i parasites…)
it
)
Physical agents (e.g. radiation, heat….)
Drugs & chemicals
M t
Maternal
l factors
f t
(e.g.
(
diabetes
di b t mellitus,
llit
h
hypertension,
t
i
phenylketonuria…….)
y
History of growth & Development
y
P
Previous
i
investigations
i
ti ti
2. Physical examination:
General principles:
y
y
y
y
22
Determine if the feature is a major anomaly, minor anomaly
or a normal variant.
Compare
p
with other family
y members.
Anthropometric measurements should be used whenever
possible to quantitatively identify abnormalities.
The growth of different parts of the body and face can be
measured and the degree of abnormality is established by
calculating the difference between the finding and the
appropriate terminal value of the normal range using age,
sex and ethnic appropriate standards.
Findings
g that suggest
gg
a possible
p
underlying
y g etiology:
gy
General
y
Short stature (height below -3SD) or tall stature (height above
+3SD) (SD=standard deviation)
A short father & son with
spondylo-epi-metaphyseal
p
y
p
p y
dysplasia
23
Short female with Turner syndrome
y
Failure to thrive (height & weight below -3SD) or obesity
(weight above +3SD)
Failure to thrive
24
Obesity
Specific organ anomalies
Unusual head shape
Dolichcephaly
Brachycephaly
Trigonocephaly
Plagiocephaly
Oxycephaly
Cloverleaf skull
Brachycephaly (flat occiput)
25
Head circumference
e.g. small head “microcephaly” (head circumference below -3SD)
or large head “macrocephaly”) (HC above +3SD)
Microcephaly
26
Macrocephaly
(Hydrocephalus)
Body proportions
e.g. short spine, short limbs or long limbs…
(1)
27
(2)
Disproportionate shortening in patients with mucopolysaccharidosis (1) & an
autosomal recessive type of spondylo-epi-metaphyseal dysplasia (2)
Facial features
y Eyebrows
e.g. Synophrys (fused eyebrows)
y
Innercanthal distance
e g Hypotelorism (decreased inner canthal distance or
e.g.
hypertelorism (increased inner canthal distance)
28
y
P l b l fissures
Palpebral
fi
(slanting)
( l ti )
Upslanting of palpebral fissures (e.g. Down syndrome)
or downslanting of palpebral fissures (e.g. Noonan syndrome &
Rubinstein-Taybi sndrome)
29
y
Palpebral fissures (length)
Short palpebral fissures (the length of the palpebral fissure is
usually
y equal
q
to the distance between the two eyes
y i.e.
innercanthal distance)
Bl h hi
Blephrophimosis
i
30
Unilateral anophthalmia
(absent eye globe)
U il t l microphthalmia
Unilateral
i
hth l i ((smallll eye))
Bilateral anophthalmia
y
E
Eyes
e.g. corneal opacities, heterochromia or other eye abnormalities
Heterochromia
Corneal opacity
p
y
Albinism
Squint
31
Congenital glaucoma
Cataract
Epibulbar dermoid
Bilateral ptosis of eyelids
32
y
Nose
Short or long nose (the nose is usually 2/3 – 3/4 the length of the
distance between the nasal bridge and the upper lip)
Short nose
Sh
Heminasal aplasia
Long nose
33
y
E
Ears
Abnormal ear position (low-set, posteriorly rotated…). When
drawing an imaginary line between the outer canthus and the
occiput, usually 1/3 of the ear is above this line)
Low-set, posteriorly rotated ear
34
Low-set ears
Abnormal shape or size of the ears
Cupped simple ears
Preauricular pit
Microtia (small or dysplastic ears)
35
Cauliflower ears
Preauricular skin tags
y
Mouth & lips
Abnormal lips (thin/full, tented, down turned, cleft), big or small mouth
(macrostomia or microstomia)
Thin tented lips
Thick patulous lips
Cleft lip
Lip pits
Macrostomia
36
Microstomia
y
Philtrum
e.g. short, long or flat
Short philtrum
L
Long
flflatt philtrum
hilt
37
y
Oral cavity, tongue, palate & mandible
Tongue (e.g. macroglossia, bifid tip…)
Palate (high arched or cleft)
Uvula ((bifid or absent))
Prognathism, micrognathia (small mandible), pointed chin
Macroglossia (large tongue) with bifid tip
38
Bifid uvula
Micrognathia
Pointed chin
Hands & feet
f
Brachydactyly (short fingers or toes)
Arachnodactyly (long fingers or toes)
39
Cli d t l (incurved
Clinodactyly
(i
d fingers,
fi
usually
ll fifth finger)
fi
)
Syndactyly (fusion of digits)
40
R d ti (absence)
Reduction
( b
)d
defect
f t
Hemimelia (absent forearm & hand))
Apodia (absent foot)
41
Ectrodactyly (absent toes)
Axial hand reduction (split hands)
P l d t l ((preaxial,
Polydactyly
i l postaxial
t i l extra
t di
digits)
it )
Postaxial polydactyly
(pedunculated post minimus)
Complete postaxial polydactyly
Camptodactyly (contracture of fingers)
42
Polysyndactyly
o ysy dacty y (p
(preaxial
ea a po
polydactyly
ydacty y with
t syndactyly)
sy dacty y)
43
Nails & dermatoglyphics
Dysplastic nails with polydactyly
44
Simian crease
Abnormal flexion creases
Oth limb
Other
li b anomalies
li
Rocker bottom feet with sandal gap
between 1st & 2nd toes
Macrodactyly (large digits)
Clasped thumb (adducted & flexed)
45
Skin
e.g. pigmentation, scales, pterygium, appendages….
Facial hemangioma
Hypopigmented area
on tthe
o
e forehead
o e ead
Areas of hyper &
hypopigmentation of skin
46
Café-au-lait spots
Generalized hypopigmentation
Hyper elasticity of skin
Dry scaly skin
Skin nevus
Cutis marmorata
Hemihypertrophy
with multiple skin
nevi
47
Knee pterygium
Skin appendages
H i
Hair
Abnormal amount of hair (alopecia, hirsutism, hypertrichosis)
Alopecia
Generalized hirsutism
48
Hypertrichosis (long eye lashes)
& synophros
Abnormal hair line (low hair line or receding hair line)
Abnormal hair color (e.g. white forelock, albinism)
Receding anterior hair line
with hair hypopigmentation
Silver colored hair
49
Hypopigmentation of
hair as a part of vitiligo
Anterior hair whorl
Neck
e.g. short, webbed…
Webbed neck
Short neck
Chest
Abnormal chest shape (e.g. pectus carinatum, pectus
excavatum, short sternum)
50
Pectus carinatum
Pectus excavatum
Nipples
e.g. widely spaced, supernumerary, inverted….
Widely spaced nipples
Supernumerary nipple
51
Spine
e.g. anencephaly, encephalocele, myelomeningeocele or stigmata
of spina bifida
Anencephaly
Myelomeningeocele
52
Encephalocele
Abnormal joint shape or mobility
Hyper extensibility of wrist joint
Hyper extensibility of knee joint
(genu recurvatum)
53
Joint & bone deformities
Bow knees
54
Knee joint dislocation
Knock knees
Multiple bony fractures & deformities
Abdomen
Abdominal wall defects (omphalocele, gastroschisis)
Hepatosplenomegaly
Nephromegaly
U bili l h
Umbilical
hernia
i
G t
Gastroschisis
hi i
Hepatosplenomegaly
55
Genitalia
e.g. ambiguous genitalia
Micropenis
Clitromegaly
46,XX DSD
56
II- Confirmation of diagnosis:
Lab. tests:
I di ti
Indications
ffor chromosome
h
analysis:
l i
y
y
y
y
y
Indications for metabolic screening:
y
y
y
Multiple congenital anomalies
Ambiguous genitalia
Developmental delay with major and/or minor anomalies
History of more than 2 miscarriages
Metabolic disorders known to cause dysmorphism are lysosomal
disorders, peroxisomal disorders and disorders of cholesterol synthesis
Radiological examination for bony changes and
neuroimaging of brain structures.
Clinical course
Similarly affected family members
57
III- Intervention:
Treatment:
y
y
Symptoms
S
t
Underlying cause
Counselling:
y
y
y
Diagnosis, natural history, prognosis, management
Recurrence risk
Reproductive
Follow-up:
y
y
y
58
Identification and counselling of at risk family members
S
Surveillance
ill
ffor complications
li ti
Correction of diagnosis
Summary
y
y
y
y
59
A congenital anomaly or birth defect is an abnormality of
structure or function that is present at birth
birth.
Birth defects may be mild or serious.
The p
principles
p
in dysmorphology
y
p
gy include the
determination of the underlying pathogenic mechanism
and if it is a single system or multi-system defect.
Accurate identification of a syndrome is a necessary
prerequisite to providing a prognosis and plan of
management for the affected infant as well as genetic
counseling for the parents
parents.
Summary (Cont
(Cont.))
y
y
y
y
60
The first step towards an accurate diagnosis of a
syndrome is by extensive phenotypic analysis
analysis.
The severity and number of anomalies in a given
syndrome vary from patient to patient.
The number of malformation syndromes described is
increasing everyday.
It is better to refer to a clinical geneticist who is more
familiar with these conditions, has access to specific
laboratory studies, dysmorphology databases and is able
to interpret the results and provide genetic counselling.
counselling
U f l Resources
Useful
R
61
y
Aase JM. Diagnostic Dysmorphology. Springer, 1990
y
Jones KL
KL. Smith’s
Smith s Recognizable Patterns of Human Malformations:
Expert Consult Online and Print. 6th ed. Saunders, 2005
y
Gorlin RJ, Cohen MMJr, Hennekam RCM. Syndromes of the Head
and Neck (Oxford Monographs on Medical Genetics) 4th ed.
ed Oxford
University Press Inc. 2001
y
Hall JG, Froster-Iskenius UG, Allanson JE. Handbook of Normal
Measurements. Oxford: Oxford University Press, 1989
y
Taybi H, Lachman RS. Radiology of syndomes. Metabolic Disorders
and Skeletal Dysplasias. 5th ed. Mosby, 2006
y
Temtamy SA, McKusick VA. (1978) The Genetics of Hand
Malformations. NewYork, Alan R Liss, Inc. 1978
y
Goh DLM. Approach to a dysmorphic Individual. Bulletin 17, MITA (P)
No: 251/06/2000
U f l Resources
Useful
R
y
y
Literature search e.g. PubMed
Database search:
y
OMIM: Online Mendelian Inheritance in Man, Centre for Medical
Genetics, Johns-Hopkins University (Baltimore, M.D.) and the
National Center for Biotechnology Information, National Library of
Medicine (Bethesda, M.D.). http://www//ncbi-nlm.nih.gov./OMIM/.
y
LMD: London Medical Databases by Winter R & Baraitser M.
[email protected]
y
POSSUM: Murdoch Childrens Research Institute.
http://www.possum.net.au/
NB: Most of the figures included in this presentation are from
personal experience, few figures are retrieved from the
internet.
62